Manual delivery pump

ABSTRACT

IN A MANUAL DELIVERY PUMP DISPOSED IN A FUEL LINE THAT LEADS FROM A FUEL TANK TO A FUEL INJECTION PUMP, A PUMP INLET AND A PUMP OUTLET ARE CONNECTED DIRECTLY THROUGH A BYPASS WHEN THE MANUAL PUMP IS NOT OPERATING, SAID BYPASS IS CLOSED AND SAID INLET IS CONNECTED TO SAID OUTLET THROUGH THE PUMP WORK CHAMBER OF SAID MANUAL DELIVERY PUMP WHEN THE LATTER IS OPERATING.

23, 1971 TETSUJI AKASH| EVAL 3,565,555

vMANUAL DELIVERY PUMP Filed Aug. 4, 1969 United States Patent Oce 3,565,555 Patented Feb. 23, 1971 3,565,555 MANUAL DELIVERY PUMP Tetsuji Akashi, Azenish, and Takuji Isomura and Nizo Enomoto, Kariya-shi, Japan, assignors to Nippodenso Kabushiki Kaisha, Karya-shi, Aichi-ken, Japan Filed Aug. 4, 1969, Ser. No. 847,056 Int. Cl. E04b 21/02 U.S. Cl. 417--568 3 Claims ABSTRACT OF THE DISCLOSURE In a manual delivery pump disposed in a fuel line that leads from a fuel tank to a fuel injection pump, a pump inlet and a pump outlet are connected directly through a bypass when the manual pump is not operating; said bypass is closed and said inlet is connected to said outlet through the pump work chamber of said manual delivery pump when the latter is operating.

BACKGROUND, OBJECT AND SUMMARY OF THE INVENTION This invention relates to a manual delivery pump disposed in a main fuel line which leads, with a vertical drop, from a fuel tank to a fuel injection pump. The manual delivery pump is of the type that includes a suction-operated valve, a pressure-operated valve and a fluid path bypassing said valves. The air which accumulates in the fuel pump (injection pump) after a complete emptying of the fuel tank and the main fuel line, may be discharged through said uid path (hereinafter called bypass) into the fuel tank during refueling thereof. It is a disadvantage of known manual delivery pumps of this type that during the operation of the manual pump, fuel may be admitted from its pressure Side to its Suction side through said bypass thus decreasing the efficiency of the pump. Such a device is disclosed, for example, in U.S. Pat. No. 2,249,326. If the cross section of the bypass lis chosen small in order to maintain such a backflow at a relatively insignificant level, then the aforenoted discharge of air from the main fuel line and from the fuel injection pump is obstructed. Also, the fuel flowing through the bypass during normal operation of the engine is disadvantageously throttled, which may cause carburetion at the suction side of the bypass.

It is an object of the invention to provide an improved manual delivery pump in which the aforenoted disadvantages are no longer present.

Briey stated, according to the invention the pumping element of the manual pump includes portions which cooperate with the bypass in such a manner that the latter is fully open when the manual pump is inoperative and fully or at least nearly closed when the manual pump is in operation.

The invention will be better understood, as well as r further objects and advantages will become more apparent, from the ensuing detailed specification of a preferred, although exemplary, embodiment of the invention taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. l is an axial sectional view of the preferred embodiment with the pumping element in its position of rest; and

FIG. 2 is an axial sectional view of the preferred embodiment with the pumping element slightly displaced from its position of rest.

DESCRIPTION OF THE PREFERRED EMBODIMENT A pump housing 1 has, on the one hand, a pump inlet 1a to which a suction conduit 2 is connected which extends with a vertical drop from a fuel tank, not shown, and, on the other hand, a pump outlet 1b to which a pressure conduit 2 is connected which leads to a fuel pump, such as a fuel injection pump, also not shown. In housing 1 there is disposed a pump piston 4 which is manually displaceable against the force of a return spring 9. The side face of pump piston 4 is provided with an annular groove 5 which, in the position of rest of the piston 4 shown in FIG. l, establishes direct communication between the suction conduit 2 and the pressure conduit 2 and thus forms a bypass. The housing 1 is closed by means of a threaded cap 6, an inside radial face of which serves as an abutment for the pump piston 4 and thus determines the position of rest thereof. Between the cap 6 and the housing 1 there is clamped a sealing gasket 7, while between said inside radial face and a radial shoulder of the pump piston 4 there is disposed a sealing gasket 8.

From the pump inlet 1a to the pump work chamber 13 containing spring 9 and disposed below the pump piston 4, there extends a channel 3 which is normally closed by a suctionoperated check Valve disposed adjacent the downstream end thereof. From the pump work chamber 413 to the pump outlet 1b there extends a channel 3' which is normally closed by a pressure-operated check valve disposed adjacent the upstream end thereof. The suction valve and the pressure valve are disposed in separate cavities of housing 1, closed, respectively, by a plug 15, 15. Each said valve comprises, respectively, a movable valve element, such as a ball 10, 10', a spring 11, 11 and a valve seat 12, 12'.

The pump work chamber 13 is closed by a radial surface 14 forming part of the housing 1 and simultaneously serving as an abutment for the pump piston 4 determining the most advanced position of the latter during its delivery or pressure stroke.

OPERATION OF THE EMBODIMENT During normal operation of the engine, the pump piston 4 is continuously in its position of rest as shown in FIG. 1. In this position, direct communication exists between the suction conduit 2 and the pressure conduit 2' through the annular groove or bypass 5. Thus, fuel may flow freely from the fuel tank to the fuel injection pump. Also, the air accumulating in the fuel injection pump upon emptying of the fuel tank may freely be discharged into the fuel tank through suction conduit 2', annular groove 5 and pressure conduit 2 during the refueling operation, at which time also the pump piston 4 is cone tinuously in its position of rest.

Depending upon the position of the engine or the vehicle or depending upon the position of the fuel injection pump, it may occur that, due to an insufficient vertical drop between the fuel tank and the fuel injection pump, some air may remain in the latter. Such occurrence may lead to misring during the starting of the engine. For a complete venting of the fuel injection pump the aforedescribed manual delivery pump is operated. As the pump piston 4 is displaced from its position of rest, first the annular groove 5 moves out of alignment with respect to the pump inlet 1a and pump outlet 1b as seen in FIG. 2. As the piston 4 continues its pressure stroke, communication between the pump inlet 1a and pump outlet 1b (thus between the suction conduit 2 and pressure conduit 2') through bypass 5 is entirely interrupted. Also, as the pump piston 4 executes its pressure stroke, the fuel present in the pump work chamber 13 is forced to the fuel injection pump through the pressure valve 10', 11, 12', channel 3', pump outlet 1b and pressure conduit 2'. Thus, a pressure increase is generated in the fuel injection pump, compressing the air still present therein. The pressure stroke ends when piston 4 has traveled a distance h from its position of rest and its leading radial face abuts against the radial surface 14. This position is shown in dash-dot lines in FIG. 1. Then manual pressure is removed from piston 4 which, thereupon, urged by spring 9, executes its suction stroke. During the latter, fuel is drawn from the fuel tank through suction conduit 2, pump inlet 1a, channel 3 and valve 10, 11, 12 into pump work chamber 13. As soon as the pump piston 4 returns to its position of rest (FIG. l), direct communication through bypass 5 is reestablished -between suction conduit 2 and pressure conduit 2', so that the afore-noted compressed air may be discharged from the pressure conduit 2 through the bypass formed of annular groove 5, into the fuel tank.

It is thus seen that by virtue of the afore-described structure, on the one hand, the passage of air or the nor* mal flow of fuel during operation of the engine is not obstructed and, on the other hand, during operation of the hand delivery pump, no fuel may flow from the pressure side of said pump into the suction side thereof bypassing the pump work chamber.

That which is claimed is:

1. In a delivery pump of the known type having (A) a pumping element, (B) a pump work chamber, (C) a pump inlet and (D) a pump outlet both adapted to communicate with said pump work chamber, (E) a suctionoperated check valve disposed between said pump inlet and said pump work chamber, (F) a pressure-operated check valve disposed between said pump work chamber and said pump outlet, said delivery pump adapted to be connected by its inlet and outlet to a fuel line leading with a vertical drop from a fuel tank to a fuel injection pump, the improvement comprising, bypass means adapted to be open for establishing direct communication between said pump inlet and said pump outlet when said pumping element is in its position of rest, said bypass means adapted to be substantially closed for interrupting said direct communication when said pumping element is moved from said position of rest.

2. The improvement as defined in claim ll, wherein said pumping element is a manually operable piston adapted to execute alternating pressure strokes and suction strokes along a path and assume a position of rest at one end of said path; said pump inlet and said pump outlet merge laterally into said path at spaced locations; said bypass means is formed of a groove disposed in the side face of said piston, said groove is in alignment with both said pump inlet and said pump outlet when said piston is in its position of rest for establishing said direct communication, said groove is not in alignment with both said pump inlet and said pump outlet when said piston is absent from its position of rest for interrupting said direct communication.

3. An improvement as dened in claim 2, wherein said groove is annular and extends peripherally about said piston.

References Cited UNITED STATES PATENTS 2,249,326 7/1941 Rabe 417-435 FOREIGN PATENTS 829,874 7/1938 France 103-203 CARLTON R. CROYLE, Primary Examiner R. GLUCK, Assistant Examiner U.S. Cl. X.R. 417-435 

